| The concrete materials is composed of coarse aggregate,fine aggregate and cementing agent,and is widely used in mine tunnel support engineering.In recent years,as China government implement the restriction policy on sand mining,materials supplies of mine tunnel concrete support has became scanter.What's more,the safety and environmental problems caused by gangue discharge always trouble coal mine enterprises.Gangue shotcrete is the material that use broken coal gangue instead of the coarse and fine aggregate of traditional concrete,and used in roadway concrete support engineering.This is one of the effective method to solve the problems of gangue discharge and concrete materials shortage,which have very social and economic value.However,comparing with the traditional shotcrete,the gangue shotcrete mechanical property and supporting feature in mine tunnel change greatly.Based on the problem mentioned above,this thesis adopt the method of theoretical analysis,empirical studies and numerical simulation to analyze the damage mechanics of gangue shotcrete.In this thesis,the interaction between tunnel surrounding rock and concrete support is analyzed,the optimized matching parameters and mechanics features of gangue shotcrete is obtained,the damage mechanics mode is built and its behavior is verified,and the acoustic emission characteristics of gangue shotcrete in axial loading test is also studied.The following research results is obtained.(1)Based on spatial effects of the excavation face and E.Hoek empirical equation,the virtual support is introduce,which aim to build the tunnel mechanical model in the period of ex-excavation,before and after supporting.In addition,by using the elastic mechanical analysis method,the interaction between tunnel surrounding rock and support is studied and the calculation method is proposed.The force condition of concrete support and its control function to the tunnel surrounding rock deformation is studied.(2)The optimized shotcrete matching parameter,which have enough strength to support tunnel,is obtained by mechanics testing.And the influence of matching style and sand ratio is analyzed.The stress-strain and other mechanics feature is also studied.(3)By using statistical damage mechanics and numerical simulation(PFC)method,the gangue concrete damage mechanics model is built and the calculation method is proposed.The numerical model is built and its parameters is proposed.Furthermore,the fracture development behavior is also studied.(4)The Acoustic Emission of concrete under axial compressive is tested.The Acoustic Emission signal changing behavior is analyzed.And the differences of AE characteristics between gangue concrete and traditional concrete is studied. |
PDF Full Text Request